638920839663 has 6 divisors (see below), whose sum is σ = 922885657304. Its totient is φ = 425947226436.

The previous prime is 638920839659. The next prime is 638920839673. The reversal of 638920839663 is 366938029836.

638920839663 is a `hidden beast` number, since 6 + 38 + 9 + 208 + 396 + 6 + 3 = 666.

638920839663 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 638920839663 - 2² = 638920839659 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 638920839663.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638920839653) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35495602195 + ... + 35495602212.

Almost surely, 2^638920839663 is an apocalyptic number.

638920839663 is a deficient number, since it is larger than the sum of its proper divisors (283964817641).

638920839663 is a wasteful number, since it uses less digits than its factorization.

638920839663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70991204413 (or 70991204410 counting only the distinct ones).

The product of its (nonzero) digits is 60466176, while the sum is 63.

The spelling of 638920839663 in words is "six hundred thirty-eight billion, nine hundred twenty million, eight hundred thirty-nine thousand, six hundred sixty-three".